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C. S. BACHOFER 



ation was begun is indicated by the first arrow at 90 minutes, and the 

 average time at which x-irradiation was terminated is indicated by the 

 second arrow. ( For U V irradiation, the second arrow would be moved some- 

 what to the right.) No irradiation was involved; the arrows simply indicate 

 the times at which the nerve cords were x-irradiated in subsequent experi- 

 ments. The relatively flat plateau during irradiation should be noted. 

 No nerve was irradiated until it had passed through a 90 minute period of 

 stabilization on the recording electrodes. The effects of x-irradiation on 



10 



20 30 40 50 



MINUTES OF X-IRRADIATION 



Fig. 8. Relative spike amplitude of giant nerve fibers of earthworm, plotted as a 

 function of time of x-irradiation. Values plotted represent ratios of activities at desig- 

 nated times, relative to activity at beginning of x-irradiation, designated by arrow. Dose 

 rate: 6 kr per min. (46 experiments). 



